ARS researchers hope that by unlocking the secrets
of the catfish genome, commercial catfish producers like this one in Columbus,
Mississippi, will be able to increase production levels. Click the image for
more information about it.

Genetic Findings Could Boost Catfish Quality and Grower
Profits

Traditionally, the catfish is looked
upon as a bottom-dweller. However, the farm-raised catfish is the most
important fish in U.S. aquaculture, and Agricultural Research Service (ARS) scientists are working to improve its
potential.

By unlocking the secrets of the catfish genomeits total genetic
informationresearchers at the ARS Catfish Genetics Research Unit (CGRU)
in Stoneville, Miss., are looking for the best way to select catfish broodstock
with superior genetic qualities. In Mississippi alone, catfish production is
worth about $245 million annually, so there is keen interest in improving the
industry's efficiency.

The catfish genome, about one-third the size of the human genome, contains
about one billion bases of genetic material called DNA. Led by CGRU molecular
biologist
Geoff
Waldbieser, geneticist
Brian
Bosworth and molecular biologists
Dan
Nonneman and
Sylvie
Quiniou used high-throughput DNA technology to identify tens of thousands
of active catfish genes and nearly 10,000 variable DNA sequences called
"microsatellites." Now they're searching for favorable, natural
variations within genes that control important traits such as lean growth,
carcass yield and improved survival in commercial ponds.

Finding the first catfish microsatellite sequences allowed Waldbieser to
develop a DNA fingerprinting system. That was a crucial first step toward
identifying distinct genetic populations, because all channel catfish look very
much alike. By using several selected microsatellites as DNA markers,
Waldbieser was able to identify the parents of egg masses, or
"spawns," collected from ponds and determine which individual catfish
reproduced.

Prior to this discovery, researchers could only know that certain broodfish
were in a pond, but they couldn't tell which fish were parents of the spawn
they collected. The DNA technology enabled the researchers to identify
same-year spawns that were related to the same father.